AIR CONDITIONING • SERVICES & GUIDESBucurești & Ilfov · 0764 012 943
RO 0764 012 943

Sanitised in May, by August it smelled of mould again – why so fast?

Editorial guide · Updated 18 September 2026

In short Short answer: 3 months is too short for a complete sanitising, but it is exactly how long it takes if something was skipped – usually the fan roller or the pan – or if the unit is switched off wet every evening in a room with an open kitchen. Most likely a combination: partial cleaning plus perfect recolonisation conditions.

This page explains a situation in an editorial format. It is not an open discussion board or a verified customer review. Contact us on WhatsApp about your own appliance.

Situation discussed

Titan, Câmpia Libertății street, 1980 block, 12,000 BTU Samsung, 5 years old, living room with open kitchen. Had it sanitised in May by a company (not sure of the method, they had a cover and washed). By August, mould smell again. They say it is normal. Is it? What did I do wrong?

Editorial explanation · Revizie AC

What is really happening

Biofilm does not start from zero after a partial wash: if colonies remain on the back of the evaporator, inside the roller or in the pan sludge, they repopulate the whole surface within weeks, because they have moisture, temperature and, with an open kitchen, plenty of food. Studies measuring cleaning effectiveness show over 99% reductions only when all components are washed, including the roller – which many companies merely 'spray' because it is hard to reach. Add the habit of switching off wet: a damp evaporator every night is a daily incubator. It is not 'normal' – it is a predictable result of the two.

Explanatory diagramWhat a visible deposit can show
What a visible deposit can show
  1. A picture can document visible deposits.
  2. Colour and appearance do not reliably identify microorganisms.
  3. The appropriate assessment depends on the issue; a photo is not a laboratory test.
What the studies say
  • Washing with alkaline detergent, brushing and high-pressure rinsing reduces fungi inside the unit by more than 99%. [Indoor Air, 2023]
  • The blower (cross-flow fan) is the most fungus-contaminated component of a split unit, more than the filter or the front of the evaporator. [Indoor Air, 2023]
  • Air conditioners in Japanese homes host distinct bacterial communities on each component, showing that every part must be cleaned separately. [CORE (open access repository), 2015]
  • Manufacturers recommend running the unit in fan-only mode for several hours to dry the interior before long periods of non-use, precisely to prevent odour and mould. [Daikin Europe, 2020]

What we do on site

  1. Inspection and photos – we show you exactly where dirt was left from the previous visit, without commenting on the company.
  2. Collection cover; cleaning solution on evaporator (both faces), roller (inside and out), pan, hose.
  3. Pressure wash in place; we check the roller by rotating it fully.
  4. Sanitising solution on everything.
  5. Outdoor unit, washed in place.
  6. We leave the drying rule written on a note stuck to the remote. See current rates on the Prices page.

What you can do yourself

  • 'Fan' 30 minutes every evening before shut-off – set a timer.
  • Hood on with every cooking session; unit off while frying.
  • Filters weekly, not fortnightly, as long as the kitchen opens onto the living room.

What NOT to do

  • Do not accept 'it is normal' as an answer at 3 months.
  • Do not ask for 'indoor only' to save money – a clogged outdoor unit strains the system and changes the condensate regime.
  • Do not spray between sanitisings.

Prevention

With all components washed and daily drying, a living-room unit with an open kitchen stays clean a whole season, often two. Annual sanitising, in spring.

When to call us

0764 012 943, Monday–Saturday 08:00–20:00. If the smell returns within 3 months after our visit, we come back free of charge.

Grey-brown dirty water flowing through the hose into the white bucket on the foil
Grey-brown dirty water flowing through the hose into the white bucket on the foil
Ask your question Report an error

Related threads

Read also

Sources (6)

The information on this page is educational and based on cited sources; it does not replace medical advice. We do not do repairs, installation or refrigerant circuit work.